GI viruses

Question 1

List two groups of viruses that infect the GI tract

Answer 1

Enteroviruses- do not cause diarrhea

Viruses with the primary symptom of diarrhea

Question 2

List the four groups that comprise the enteroviruses

Answer 2

Polioviruses
enteroviruses
coxackie viruses
echoviruses

Question 3

Enteroviruses are shed in large numbers in the feces, are acid stable, and resist _____

Answer 3

alcohols and detergents

Question 4

List six syndromes that are consistently present in enterovirus infection

Answer 4

Rash (all except polio)
aseptic meningitis
pericarditis/ myocarditis
paralysis
hepatitis 
colds

Question 5

What type of virus is most stronly associated with myocarditis

Answer 5

coxackie viruses

Question 6

A high percentage of enterovirus infections are _____ especially in children

Answer 6

asymptomatic

Question 7

Diagnosis of enterovirus is primarily based on:

Answer 7

clinical presentation- many strains, so specific testing is limited AND there are no specific therapies so identifying the specific virus is not useful

Question 8

True or false: there are no antivirals available for enteroviruses

Answer 8

True

Question 9

What is the best approach to treating enteroviruses?

Answer 9

1. start with prevention- hand hygiene, food handling
2. vaccines for hepatitis A and polio virus
3. mostly self limited illnesses, supportive care as necessary

Question 10

How is polio virus transmitted?

Answer 10

Fecal-oral route, replicates in gut mucosa.

Enters through Peyer’s patches and M cells in the gut

Question 11

For all members of the enterovirus, CNS disease requires ______ and _______

Answer 11

high viral titers

persistent secondary viremias

Question 12

What causes paralysis in polio infection?

Answer 12

Viral replication in and killing motor neurons of the anterior horn of the spinal column

Question 13

Describe post-polio syndrome:

Answer 13

nervous system recovers in young people so mild paralytic damage is “masked”
as people age, they become less able to compensate for CNS damage and the original paralytic symptoms return
NOT due to return of polio virus

Question 14

List families of viruses associated with diarrhea

Answer 14

Major: rotavirus, norovirus, astrovirus

Some serotypes of adenovirus and coronavirus

Question 15

Describe the transmission of viruses that cause diarrhea

Answer 15

transmitted by the fecal-oral route, are very stable, are acid resistant, and large amounts of
virus are shed in stools

Question 16

True or false: shedding of virus stops as soon as diarrhea symptoms subside

Answer 16

False, continued shedding for extended periods of time

Question 17

In the US, rotavirus has a seasonal peak in the _____

Answer 17

winter

Question 18

True or false: most people are seropositive for rotavirus by age 4

Answer 18

true, 90%

Question 19

Describe the clinical syndrome of rotavirus infection

Answer 19

1-3 day incubation periods
abrupt onset of watery stools that become clear as colonic material is flushed out
fever is possible but would be mild
usually self limiting, high mortality in resource poor areas due to dehydration

Question 20

What tests exist to diagnose rotavirus infection

Answer 20

electron microscopy
ELISA antigen capture assay that uses stool samples

** no antivirals, so usually make dx based on season, pt age, clinical presentation

Question 21

What is the best strategy for preventing rotavirus infection?

Answer 21

Live attenuated vaccine

Safe food and water supplies

Question 22

Describe the epidemiology of norovirus

Answer 22

No seasonality
extremely contagious- outbreaks in schools, institutional settings, cruise ships high rates of infection in household contacts
thought to be the cause of 30% of gastroenteritis in older children and adults

Question 23

Describe the clinical syndrome of norovirus

Answer 23

Abrupt onset of diarrhea, nausea, vomiting, abdominal cramps

Self limiting, resolves within 24-48 hours

Question 24

Describe the transmission of norovirus

Answer 24

fecal-oral route, via contaminated food or water

Question 25

How is diagnosis of norovirus made?

Answer 25

Clinical presentation
Public health my follow local outbreaks

No culture, possible but not practical to do electron microscopy, RT-PCR
- no antivirals so therapeutic focus is on avoiding dehydration

Question 26

Describe the epidemiology of astroviruses

Answer 26

Common cause of viral gastroenteritis

75% of children 4 years old are seropositive

Question 27

Describe the clinical presentation of astrovirus

Answer 27

3-4 day incubation then diarrhea, nausea, headache, malaise for 2-4 days.
Vomiting can occur but not as common as in norovirus
Fever is not common

Question 28

How is diagnosis of astrovirus made?

Answer 28

Symptoms and age of patient
No culture, possible to do electron microscopy on stool but not practical
NO vaccines or antivirals

Question 29

What is the best way to prevent astrovirus infection?

Answer 29

hand washing, good hygiene, proper food handling and preparation procedures,
and clean water supplies.

Question 30

Describe symptoms seen in adenovirus gastroenteritis

Answer 30

Short incubation period

Acute onset of diarrhea, nausea, occasionally vomiting, possible low grade fever

Question 31

What strains of adenovirus cause GI illness?

Answer 31

40,41, 38

Question 32

Gastroenteritis caused by coronavirus is most commonly seen in ________

Answer 32

children, under 1 yr of age

Question 33

Describe the clinical presentation of coronavirus

Answer 33

Gastroenteritis is diarrhea that has occult blood, is less water and more mucoid

coronavirus also causes colds, SARS

Question 34

Of all the viruses that cause diarrhea there is a vaccine for only one:

Answer 34

rotavirus

Question 35

Describe current thinking on why enterovirus does not cause diarrhea but other gastroenteric viruses do

Answer 35

Structural protein of rotavirus acts similarly to cholera toxin, there is a capsid protein on astrovirus that is a toxin that disrupts actin filaments, coronavirus causes inflammation that leads to the occult blood and mucus in the stool

thought that other enteric viruses might have toxic activity